Process for producing metals and alloys



Patented Mar. 3, 1931 PATENT OFFICE TUBE ROBERT HAGLUND, OF STOCKHOLM,SWEDEN PROCESS FOR PRODUCING METALS AND ALLOYS No Drawing. Applicationfiled July 31, 1924, Serial No. 729,354, and in Sweden October 8, 1923.

The present invention relates to a process for producing metals andalloys, which makes it possible to obtain an improved regulation of thequantity of metals to be alloyed with a metal or alloy as compared withthe results of hitherto known processes for the production of metals andalloys in electric furnaces. The chief object of the invention is aprocess for reducing metals and alloys with a low percentage of carbonbut the process may in many cases also be used with. great advanta e forthe production of metals and alloys with higher percentages of carbon.In the hitherto known electro-metallurgical processes Where carbon orcarboniferous reducing agents are used, the ores or other raw materials,from which the metals or alloys are to be produced, are reduced eitherdirectly with carbon or, as is the case when producing pig iron, partlywith carbon and partly with the carbon-mono-oxide containing gasesformed in the process. To produce a product with low percentage ofcarbon by such means has as a rule hitherto not been possible. Insteadit has been necessary, in order to get such a product with lowpercentage of carbon,

to refine the product with great costs.

The present process renders it possible to produce directly metals andalloys with low percentage of carbon, even such metals and alloys thatwill easily absorb carbon. This object is attained by reducing the oreor the like entirely or mainly not directly but-indirectly with carbonor carboniferous reducing agents. A suitable mixture of oxidiferousmaterial and carboniferous reducing agents are formed into bricks orlumps of rectangular or other form which lumps are charged in a furnacetogether with the ore or the like from which the. metal or alloy is tobe produced. The ingredients for the bricks or lumps should bepulverized and intimately mixed. The specially prepared material in thelumps will first be reduced in the furnace r and the metal or the likethus produced will in its turn act as a reducing agent upon the othermaterial.

The oxidiferous materials in the bricks or lumps must be of such qualitythat, when it is 5 reduced by carbon, such elements, alloys or carbidesare formed, as will have a reducing action upon the raw material properfor the metal or alloy to be produced. For example the following oxidesmay be used as an ingredient in the bricks or lumps, namely alumlnumoxide, magnesium oxide, barium oxide, calcium oxide, silica, manganeseoxide, boric acid, chrome oxide, zinc oxide and others. Each of theseoxides or a mixture of two or more of them may be used in the bricks orlumps, different sorts of which may be used together. It may beadvantageous to use special agents in the process for getting a suitableconsistency and melting point of the slag and such agents may be mixedinto the bricks. As a rule, however, it will be more suitable to addseparately such agents, that are not to be influenced by the reducingcarboniferous agents. These agents which naturally must be chosen withdue regard to the nature of the oxidiferous materials in the bricks orlumps and of the slag forming ingredients in the other materials mayconsist of lime, quartz, fluor-spar, sulfides such as Gas and others. Asreducing agents in the bricks or lumps one or more carboniferousmaterials may be used such as charcoal, graphite, anthracite, coal,lignite, coke, lignite coke (or dust or grits of said Carboniferousmaterials), peat, sawdust and others. If a carboniferous material otherthan a coke is an ingredient in the bricks or lumps thesemay bepreviously heated to make the fuel to coke. This will also make thebricks hard and porous. A binding agent for the content of the bricks orlumps may, if necessary, be used such as the usual agents forbrick-making namely tar, marl, lime-water, clay, waterglass, sulphite,waste lye and others. VVhen bricks of special strength are required theymay be previously sintered or burnt.

Metals or alloys which with great advantage may be produced by thepresent process are for example, chromium, iron, manganese, titanium,vanadium, tungsten. molybdenum and alloys containing the metals named.

For the production of ferro-chromium from the commercial chromium oxideore (chromite) or for" the roduction of ferrochromium alloys with owerpercentage of chromium, for example rustless iron and steel, out ofmixtures of such ore and iron ore (or metallic iron), it is suitable touse bricks or lumps containing one or more oxides such as aluminumoxide, calcium oxide or magnesium oxide. Upon the reduction of thebricks in the furnace in this case aluminum, calciumor magnesium metalwill be produced (or, according to the percentage of carbon in thebricks, carbides, for example calcium carbide), which metals (orcarbides) will rapidly reduce the chromium oxide ore charged togetherwith the bricks or lumps. hereupon aluminum oxide, calcium oxide ormagnesium oxide will again be formed, which oxides are taken up in, theslag. As suitable aluminum oxide contain ing raw material in the bricksor lumps may be used aluminum oxide, alundum, bauxite and others. Assuitable magnesium oxide containing raw material may be used magnesiteor dolomite and others, and as suitable calcium oxide containing rawmaterial may be used limestone, burnt, lime, marl and others. As theslag forming ingredients by reduction of chromite mainly will bealuminum oxide and magnesium oxide, the slag produced may be used forthe brick-making. The temperature in the reduction zone of the furnacewill be higher than by the reduction of chromium oxide ore directly bymeans of carboniferous reducing agents, and the slag will accordingly behotter and more easily tapped than by the hitherto used processes forthe production of ferro-chromium.

If the bricks are of high specific gravity it may in some cases beadvantageous for easing the Work of the furnace to add a part of thereducing agents in'the charge in the form of lumps of carbon material,for example lumps of charcoal. Only a small quantity of such charcoalwill be needed if a specially high percentage of carbon in the alloy isnot desired. An excess of chromium oxide'ore may be eventually added forthe compensation of such additional charges of Carboniferous material.It is however more convenient to use carboniferous reducing agents inthe bricks or lumps of such quality that light and porous bricks areformed, in which case no supplementary addition of carboniferousmaterials is needed.

By using a surplus of bricks in proportion to the quantity of chromiumoxide ore it will be possible to produce chromium alloys with forexample'a high percentage of aluminum. In this case a slag of lowspecific gravity may suitably be used. As in dients in the slag,efiecting a low speci c gravity of same may be mentioned calciumsulphide, aluminumsulphide, magnesium sulphide and magnesium oxide.These named sulphides may be brought into the slag by adding charges ofmaterial already containing such sulphides, or additional, charges maybe made of some other sulfidiferous material such as sulphide of iron,magnetic lIOIl pyrite and others. These materials will during theprocess, for example by reaction with the metal reduced out of thebricks, form in the furnace one or more of the light sulphides abovementioned, whereby the iron or other metal content in the sulfidiferousmaterial is separated out.

If, however a chromium alloy with low or no percentage of aluminum is tobe produced by means of bricks or lumps containing aluminum oxide thecontent of chromium oxide ore in the charge is accordingly regulated sothat aluminum metal reduced out will wholly or substantially be oxidizedthrough reaction with the chromium oxide ore. In this case it will beadvantageous to work with a slag of comparatively high specific gravity,the reason for this being that i the reduction of the chromium oxide oremainly will take place in the zone above the slag and accordingly aquicker reduction effected than will be the case if the chromium oxidefirst-is solved in the slag from which it must be reduced out.

' Upon the reduction of bricks or lumps containing magnesium oxide orcalcium oxide, the magnesium or calcium metal will be obtained in theform of gas which vastly facilitates the reducing action on the ore.This appearance of the metal in the form of gas in the furnace will alsotake place to a great extent when aluminum metal is reduced out ofbricks. The furnaces for the production of chromium or chromium alloyswith the described method may suitably be the usual furnacesof thecarbide furnace type.

The production of other metals and alloys with the present method isefi'ected in a similar way to that described above with {eference to theproduction-of chromium aloys.

Forthe production by means of the present process of iron "or steel itis especially advantageous to determine the ingredients in the bricks orlumps and the rest of the charge in such a manner that the slag formedby the smelting has such quality as to be suitable" for the productionof cement. The working of the slaginto cement may be effected by meansof the usual methods. By means of thepresent process it will thus bepossible to produce as a by-product not only cement of the usualPortland composition but also more rapidly hardening aluminate cementand lime-aluminate cement. For the production of Portland cement theoxide containing raw material in the bricks or lumps may suitablyconsist of one or more CaO containing materials such as lime-stone, marlor burnt lime and of clay, bauxite or other A1 0 containing material andif necessary also of quartz or other SiO containing material. For theproduction of cement richer in aluminum oxide it will be best to usebauxite as an A1 0 containing raw material. The bricks or lumps aresuitably. made with use of lime-water, clay or cement as a'bindingagent. For this purpose a part of the cement obtained inv the processmay be used, therebycirculating it in the process.

If however, the production of cement clare that what I claim is:

slags is not desired, bricks may be used with a high percentage ofsilica such as for-example quartz or sand. If the iron ore con-- tainslime, bricks-may be used which contain, besides'reducing agents, mainlysilica. In other cases slag-forming materials other than silica must asa rule also be added, either forming part of the bricks or being chargedseparate. Two or more sorts of bricks or. lumps may be used, for examplebricks containing one or more .of the oxides of calcium, magnesium oraluminum and carboniferous materials together with bricks containing SiOand carboniferous materials. Slags such as for example calciumsilicatesor manganese-silicates may also be used as oxidiferolls ingredientsincthe bricks.

In this case calcium-silicid or manganesesilicid will first be formedand these silicides thereupon reduce the iron ore. Aluminiumsilicatessuch as chamotte, clays and others may also be used as suitable rawmaterials a for the bricks.

On account of the fact that the temperature in the furnace mainly isdetermined by the reduction temperature for the bricks, the productssnielted' by the process will reach' a higher temperature than willbethe case when producing for example pig iron in the usual way in anelectric furnace.- Thus the temperature will be sufliciently. high ,evenfor the tapping of iron with low content of carbon. u

- If the bricks or lumps are'used in excessof iron ore, the iron may beobtained with the metal reduced out of'the bricks, for example silicon,manganese, aluminum, chromium and others. If however such amount of ironore is used that a part of the iron oxide remains, un'reduced in thecharge, it is possible by the present method to'obtain a product poor incarbon and other alloy ingredients. This product should h o\\'cvcr,-as arule, be subsequently treated in specialv electric furnace foradjustment of the percentage of carbon and sulfur cleaning and so on.This subsequent treatment can however be made in much shorter time andWillbe" much cheaper than the refining of pigiron. The production ofiron with the present process may if the iron ore mainly is in form oflumps be carried out in the usual electric shaft furnace.' If the ironore is finely granulated or pulverized it will be more advantageous towork in an electric furnace of the carbide furnace type.

' For the production bythe present method .of metals and alloys withextremely low percentage of carbon, the quantity of carboniferousmaterial in the bricks or lumps should-as a rule be less than thequantity of carbon required for the complete reduction of theoxidiferous material in the bricks or lumps.

Having thus described my invention I deprises reducing ores by fusingthem in an electric furnace together with a quantity of reducing agentfor the ores added in the 'form of lumps of material containing bauxiteand carbonaceous reducing agents and lumps of materialcontaining'magnesium oxide material and carbonaceous reducing agents.

3. A process for producing ferro-chromium alloys, which comprisesreducing chromite ore by fusing it in an electric furnace together witha quantity of carbonaceous reducing agents added for the greater part inthe form I of ingredients of lumps of material containing in addition tothe carbonaceous agents a considerable amount of magnesium oxide.

4. Process for producing the elements with atomic number from22 to 26 inthe periodic system, or alloys containing at least one of said elements,which comprises preparing a chargecontaining an oxide of at least one ofsaidelements and at least one oxide having a heat of formation equal toor higher than that of said first oxide; and carbon reducing agents inamounts insuflicient for the reduction of more than a part of the wholeoxide content; keeping in the unfused condition the oxide of the firstnamed kind, keepm sald oxide, compared with the last named k nd, in

less intimate contact with the reducing agents by adding aconsiderablepart'of the carbon reducing agents in. the form oflumps,said. lumps besides the reducing agents containing mainly an oxide ofthe last named kind; and reducm the oxide oft-he first named kind byfusing tlle charge in an electric furnace.

5. Process of producing the elements with atomic number from 22 to 26 inthe periodic system, namely titanium, vanadium, chromium, manganese oriron, or alloys containing at least one of said elements, whichcomprises preparing a charge containing an ox ide ore of at least one ofsaid elements and at least one of the oxides of aluminum, mag

tion of more than a part of the whole oxide content; keepingin theunfused condition the oxide of the first named kind, said oxide,compared with the last named kind, being kept in less intimate contactwith the carbon material by adding at least a considerable part of thecarbon reducing agents in form of lumps which besides the reducingagents mainly contain a considerable amount of at least one of theoxides of aluminum, magnesium and calcium; and reducing the oxide of thefirst named kind by fusing the charge in an electric furnace.

6. Process for producing ferrochromium alloys, which comprises preparinga charge containing chromite ore and material containing at least one ofthe oxides of aluminum, magnesium and calcium, and carbon reducingagents in amount insuflicient for the reduction of the whole content ofoxides of iron and chromium; keeping in the unfused condition thechromite compared. with the material containing at least one of theoxides of aluminum, magnesium and calcium,

' said chromite being kept in less intimate contact with the'carbonmaterial by adding at least a considerable part of the carbon ma terialin the form of lumps, said lumps besides the carbon'material mainlycontaining at least one of the oxides of aluminum, magnesium andcalcium; and reducing the oxides of iron and chromium out of thechromite by fusing the charge in an electric furnace.

7. Process for producing chromium-alloyed iron or steel, which comprisespreparing a charge containing chromite ore and iron and a materialcontaining at least one oxide which has a higher heat of formation thanthat of chromium oxide; and carbon reducing agents in amountsinsufiicient for the reduction of more than a part of the whole oxidecontent; keeping in the unfused con- 7 dition the chromite andthe iron,said materials, compared with the oxide of the higher heat of formation,being kept in 'less intimate contact with the carbon material by addingat least a considerable partof the car- 'bon material in form of lumps,which besides the carbon material mainly contain an oxide of .the lastnamed kind; and reducing the oxide in the chromite ore by fusing thecharge.

in an electric furnace.

8. Process of producing chromium-alloyed iron or steel, which comprisespreparing a charge containing chromium oxide ore. iron ore, materialcontaining at least one of the oxides of aluminum, magnesium andcalcium, and carbon reducing agents in amounts insufficient for thereduction of the whole .content of oxides of iron and chromium,

intimate contact with the carbon material by adding a portion of thereducing agents as

